1. Field of the Invention
The present invention concerns a method for graphically assisting the navigation of an instrument (in particular a medical instrument, in particular a needle and/or a guide sleeve guiding a needle) within a procedure region of a target object (in particular a patient) using a magnetic resonance device, wherein coordinates of a target position and/or target region that is to be accessed are obtained from a high-contrast image data set acquired with the magnetic resonance device. The invention additionally concerns an associated magnetic resonance device.
2. Description of the Prior Art
Minimally invasive procedures, primarily in the field of medicine, are implemented with increasing frequency within a magnetic resonance device. Magnetic resonance is superbly suitable for examination planning since it offers the advantage of a very good soft tissue contrast, such that anatomical features (for example blood vessels or nerves) can also be addressed in the procedure planning, in particular the planning of a puncture channel with a needle. For this purpose, it is known to execute a three-dimensional high-contrast acquisition, in order to acquire a high-contrast image data set from which both coordinates of a target position and/or target region to be addressed can be obtained, and the remaining planning of the procedure can ensue; for example, using a procedure with a needle. This planning is for the purpose of designating the point on the skin on the patient at which the needle should be inserted, the angle at which it is to be introduced, and the defined distance by which the needle is to be displaced.
In spite of the poor accessibility in a magnetic resonance device where the patient is supported in the isocenter inside the patient receptacle, this modality, due to the cited advantages, has an increasing popularity. There, however, is a further disadvantage of magnetic resonance imaging. Fast imaging, as is required for a real-time representation of the needle (or a guide sleeve, for example), has only a poor soft tissue contrast, resulting in low-contrast image data. Although the needle can be clearly shown with such a fast imaging (which, for example, shows the feed of a needle—for example a biopsy needle—with three images per second), the contrast at the target position/target region is no longer sufficient.
To solve this problem, it has been suggested to regularly interrupt the procedure in order to interpose a high-contrast scan that then allows the assessment of whether the target position or, the target region is hit. However, this extends the procedure and entails the risk of patient movement.